Model, software, and database for computation of line-mixing effects in infrared Q branches of atmospheric CO2 - I. Symmetric isotopomers

R. Rodrigues, K.W. Jucks, N. Lacome, Ghislain Blanquet, Jacques Walrand, W.A. Traub, B. Khalil, R. Le Doucen, A. Valentin, C. Camy-Peyret, L. Bonamy, J.-M. Hartmann

    Research output: Contribution to journalArticlepeer-review

    Abstract

    A theoretical model based on the energy-corrected sudden approximation is used in order to account for line-mixing effects in infrared Q branches of symmetric isotopomers of CO. Its performance is demonstrated by comparisons with a large number (about 130) of CO-N and CO-O laboratory spectra recorded by several instrument setup: nine Q branches of different vibrational symmetries lying between 4 and 17 μm are investigated in wide ranges of pressure (0.05-10 atm) and temperature (200-300 K). The model is used to generate a set of suitable parameters and FORTRAN software (available by ftp) for the calculation of the absorption within CO. CO, and CO infrared Q branches under atmospheric conditions, which can be easily included in existing radiance/transmission computer codes. Comparisons are made between many (about 280) computed atmospheric spectra and values measured using two different balloon-borne high-resolution Fourier transform instruments: transmission (solar occultation) as well as radiance (limb emission) measurements of seven Q branches between 12 and 17 μm for a large range of atmospheric air masses and pressure/temperature conditions have been used, including the v band of both CO and CO. The results confirm the need to account for the effects of line-mixing and demonstrate the capability of the model to represent accurately the absorption in regions which are often used for temperature/pressure sounding of the atmosphere by space instruments. Finally, quantitative criteria assessing the validity of the widely used Rosenkranz first-order approximation are given.
    Original languageEnglish
    Pages (from-to)153-184
    Number of pages32
    JournalJournal of Quantitative Spectroscopy and Radiative Transfer
    Volume61
    Issue number2
    DOIs
    Publication statusPublished - 1 Feb 1999

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